1. Field of the Invention
The present invention relates to an endoscopic fluid passage changeover valve unit which includes a cylinder portion having a hollow portion formed therein and which changes, in a region located to a downstream direction side from the hollow portion, fluid passages to supply a fluid that has passed through the hollow portion. The present invention also relates to an endoscope including this endoscopic fluid passage changeover valve unit.
2. Description of the Related Art
Jpn. Pat. Appln. KOKAI Publication No. 2003-52621 and Jpn. Pat. Appln. KOKAI Publication No. 64-2620 have each disclosed an endoscope in which a gas (air, carbon dioxide) and water are supplied as fluids to a distal portion of an insertion section. In each endoscope, an endoscopic fluid passage changeover valve unit is attached to a holding casing of an operation section. The endoscopic fluid passage switching valve unit includes a cylinder portion fixedly attached to the holding casing, and a shaft attached to the cylinder portion to be inserted in a hollow portion formed in the cylinder portion. The shaft is movable relative to the cylinder portion along a movement axis. A downstream end of an upstream-side gas supply passage and an upstream end of a downstream-side gas supply passage are in communication with the hollow portion, and a downstream end of an upstream-side water supply passage and an upstream end of a downstream-side water supply passage are in communication with the hollow portion. A communication passage which communicates the hollow portion with an outside of the holding casing is formed in the shaft, and the communication passage is open to the outside of the holding casing through an opening. In the hollow portion, the upstream-side gas supply passage, the downstream-side gas supply passage, and the communication passage are not in communication with the upstream-side water supply passage and the downstream-side water supply passage.
In Jpn. Pat. Appln. KOKAI Publication No. 2003-52621, the shaft is movable relative to the cylinder portion along the movement axis between a first input mode and a second input mode. In the first input mode, the communication between the upstream-side water supply passage and the downstream-side water supply passage is blocked in the hollow portion. Therefore, in the first input mode, water is not supplied to the downstream-side water supply passage from the upstream-side water supply passage. In the first input mode, the upstream-side air supply passage is in communication with the downstream-side air supply passage and the communication passage in the hollow portion. Here, when the opening of the communication passage is not blocked by, for example, a finger of a surgeon in the first input mode, the air which has passed through the upstream-side air supply passage flows to the outside of the holding casing from the opening through the communication passage. In this case, the air is not supplied to the downstream-side gas supply passage from the upstream-side gas supply passage. On the other hand, when the opening of the communication passage is blocked by, for example, the finger of the surgeon in the first input mode, air is supplied to the downstream-side gas supply passage from the upstream-side gas supply passage, and the air supply is performed in the downstream-side gas supply passage.
The shaft is then moved toward an axially parallel inward direction from the first input mode, and is thereby set in the second input mode. In the second input mode, the communication of the upstream-side air supply passage with the downstream-side air supply passage and the communication passage is blocked in the hollow portion. Therefore, in the second input mode, air is not supplied to the downstream-side gas supply passage and the communication passage from the upstream-side gas supply passage. In the second input mode, the upstream-side water supply passage is in communication with the downstream-side water supply passage in the hollow portion. Therefore, in the second input mode, water is supplied to the downstream-side water supply passage from the upstream-side water supply passage, and the water supply is performed in the downstream-side water supply passage.
In the endoscopic fluid passage changeover valve unit according to Jpn. Pat. Appln. KOKAI Publication No. 64-2620, two elastic springs extend parallel to each other along the movement axis. The two return springs are different in elastic constant from each other, and connect the cylinder portion to the shaft. Since the two elastic springs are provided, the shaft is movable relative to the cylinder portion along the movement axis between the first input mode and the second input mode and between the second input mode and a third input mode.
In the first input mode, the communication between the upstream-side water supply passage and the downstream-side water supply passage is blocked in the hollow portion. Therefore, in the first input mode, water is not supplied to the downstream-side water supply passage from the upstream-side water supply passage. In the first input mode, the communication of the upstream-side gas supply passage with the downstream-side gas supply passage and the communication passage is blocked in the hollow portion. Therefore, in the first input mode, carbon dioxide is not supplied to the downstream-side gas supply passage and the communication passage from the upstream-side gas supply passage. In this case, carbon dioxide does not flow to the outside of the holding casing from the opening.
The shaft is then moved toward the axially parallel inward direction from the first input mode, and is thereby set in the second input mode. In the second input mode, the communication between the upstream-side water supply passage and the downstream-side water supply passage is blocked in the hollow portion. Therefore, in the second input mode, water is not supplied to the downstream-side water supply passage from the upstream-side water supply passage. In the second input mode, the upstream-side gas supply passage is in communication with the downstream-side gas supply passage and the communication passage in the hollow portion. When the opening of the communication passage is closed by, for example, the finger of the surgeon in the second input mode, carbon dioxide is supplied to the downstream-side gas supply passage from the upstream-side gas supply passage, and a supply of carbon dioxide is performed in the downstream-side gas supply passage.
The shaft is then further moved toward the axially parallel inward direction from the second input mode, and is thereby set in the third input mode. In the third input mode, the communication of the upstream-side gas supply passage with the downstream-side gas supply passage and the communication passage is blocked in the hollow portion. Therefore, in the third input mode, carbon dioxide is not supplied to the downstream-side gas supply passage and the communication passage from the upstream-side gas supply passage. In the third input mode, the upstream-side water supply passage is in communication with the downstream-side water supply passage in the hollow portion. Therefore, in the third input mode, water is supplied to the downstream-side water supply passage from the upstream-side water supply passage, and the water supply is performed in the downstream-side water supply passage.